This application proposes to study whether expertise mitigates age declines in pilots' performance in situations of environmental support for use of domain knowledge. Pilots will listen to and repeat air traffic control (ATC) messages (standard ATC communication procedure) in the laboratory. This task will be extended in order to examine which task factors support mitigation and how. Ultimately, the task will be integrated into simulator-based studies to allow investigation of communication ability in a task environment that provides more opportunity for support while increasing overall demand. The impact of expertise, age, and task factors on communication errors, time, and recall will be studied. The proposal asserts that the obtained results will not only address issues of aging and pilot communication, but also elucidate the relationship of domain knowledge and the role of the task environment to mitigation of age-related declines.